Throttle valve mechanism for fluid actuated rotary tools



March 7, 1950- E. R. WHITLEDGE THRoTTLE VALVE MECHANISM FOR FLUID ACTUATED ROTARY TooLs 2 sheets-shea v1 Filed Jan. 30, 1946 EDGAR R. WHITLEDGE s Y E N R 0 T T A Marc-h 7, 1950 E. R. WHITLEDGE 2,499,708

THROTT VALVE MECHANI FLUID IUATED ROTARY 0 Filed Jan. 30, 1946 2 Sheets-Sheet 2 l INVENTOR. EDGAR R. WHITLEDGE BY al M14, f

ATTORNEYS Patented Mar. 7, 1950 'rnao'r'rLE vALve MECHANISM ron FLUID AorUA'rEn normar r.rooLs Edgar R. WhitledgefMantua, Ohio, assigner, by

mesne assignments, to Reed Roller Bit vCompany, Houston, Tex., a corporation of Texas Application January 30, 194'6QSerial No."644,372

(Cl. HB2-084) 7 Claims.

This invention relates to improvements in rotary power tools, such as screw drivers, nut runners, and the like. More particularly the invention has todo with automatic means for operating the throttle valve of a fluid motor by which the tool is driven in a manner such that when the tool is pressed against the work the power cornes on automatically.

One of the objects of the invention is the provision of a power tool with automatic control means.

Another object is the provision in such a tool of lautomatic control means which may be readily removed, after which the tool `may be controlled manually in the usual manner.

Another object is the provision in a tool of the character describedof clutch elements spring biased out of engagement, but adapted to engage when the tool is pressed against the work, with means responsive to such clutch-engaging movement for automatically opening a throttle valve and supplying pressure fluid to the motor which drives the tool.

Still another object is to prov-ide a tool which combines with such automatic application of power, means for cutting oil the power when the torque exertedl for turning the work reaches a predetermined level.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawingainwhich Fig. 1 is a longitudinal sectional view of a power screw driver embodying the invention, the parts being Vshown in their idle position with the control valve closed.

Fig. 2 is a similar View with the control valve open and the tool doing work.

Figs. 3 and 4 are perspective views of the driv ing and driven clutch elements respectively.

Fig. 5 is a front end view of the tool, partly in section, and

Fig, 6 is a fragmental detail view illustrating the vinterengaging cam faces on clutch elements employed in connection with the invention.

The particular embodiment of the invention herein illustrated comprises a cylindrical casing l0, a backhead Il and a clutch housing i2, the two latter parts being threadably engaged with the casing Iii at I3 'and i4. A tting l5 designed to be mounted at one end of a iiexible compressed air tube, not shown, may be threaded 'into the backhead Il as shown. The cavity in which the tting is mounted is in communicationwith a I2 short passage it leading to a valve chamber il. A shouldered part of this chamber serves as a seat for a poppet valve E8 which is rigid with 'a plunger i9 that slides in a bore 2E! and lextends out ybeyond the backhe'ad H in order to constitute means for opening the valve against the action of a coil spring 2l that abuts against the head of the valve and against ya hollowed out screw plug 22 which functions also to close one end of the valve chamber. When the valve is unseated air is admitted into the bore 2B vand through a passage not shown into an annular space 23 which is in register with one or more passages 24 in a bearing plate 2-5, which passages in turn register with one or more passages 26 in a cylinder 2l which ts within the casing Ill; From the passages 2t the ilu'idis directed against. blades or vanes 28 of a rotor 29carried by shaft Si) which has bearing at its upper end in bearing plate 25 and at itslower end in a second bearing plate 3l. The exhaust fluid passes into an an-v nular chamber 32 and through one or more ports 33 into another annular chamber 34 under a deliector ring 35 and thence through a slot 36 in the ring out to atmosphere. The fluid motor which has just been 'described is of conventional construction and the details thereof form nopart of the present invention.

On the lower end of shaft 3l! there is formed a pinion 3l constituting the sun gear of a planetary reduction gear assembly. This pinion meshes with two or more planet gears 38 that run upon a xed ring gear 39. Gears 38 have short shafts 4!) rotatably mounted in a planet carrier All which has bearing in a bushing 42. Carrier 4l has a hollow depending portion which is internally threaded to receive the hollow upstanding shank of a driving clutch element 43, the latter running against a thrust bearing 44. Movement of the carrier in the opposite direction is limited by an out-turned flange 45 on bushing 42. Only sufficient movement of these parts is permitted lengthwise of the tool to afford free running operation. The gearing is designed to provide an appreciable .reduction in speed as be tween the motor and the clutch element 43.

The driving clutch element 43 has a lowerv surface 46 from which extend downwardly one or more clutch teeth 4l. The forwardly moving vedges or faces 48 of these teeth are beveled or inclined and are disposed to Contact complementary inclinedfaces 49 on teeth 50 projecting up wardly from a driven clutch. element 5I. The.

latter element is providedwith a pilot 52 which Aslides in a bore 53 of element 43, the two elements being biased toward disengagement by a coil spring 54 which bears at one end against pilot 52 and at the other end against the carrier 4|. Hence the clutch elements normally stand in the relation illustrated in Fig. 1 of the drawing.

Shaft 55, preferably formed integral with clutch element 5I, carries the tool to be rotated. In the illustrated case the shaft has a screw driver bit formed on its extremity. Shaft 55 has bearing in a sleeve 56 provided at its upper end with a flange 51 that ts slidably in a circular pocket 58 formed in clutch housing I2, and is adapted to seat against a shoulder 59 in the housing. This sleeve is yieldably held in the illustrated position by a coil spring 6|! that bears at its upper end against the clutch element 5|. Spring 60 is weaker than spring 54, so that normally it is overcome by spring 54 as illustrated in Fig. 1.

Driven clutch element 5| is provided with a peripheral groove 6I in which runs a shoe 52 carried at the lower end of a control member 63 which extends upwardly alongside the housing l2 and casing IU to a position opposite the rounded extremity of plunger |9. An elongated sheet metal cover or guard 64 of generally channel shape in cross-section is held at its lower end by a foot portion 65 which has an opening therethrough to rlt over a lower constricted part of clutch housing I2. At its upper end it is provided with a pair of wings 5G which are perforated to take a pin 61 that extends through them and through a registering hole in the backhead II. 10 is a block with an inclined or cam surface 'I3 on its lower side. This block is carried by a screw 'Il which is threaded through the upper end of the guard 64 so as to be adjustable up and down between the guard and the backhead Il. The free end of control member 53 is beveled off as shown at 'l2 at the same angle as the cam surface 13 on the block. In the cam surface 'I3 there is a step 'I4 providing a backstop for the outer side of member 63. When the latter member moves upwardly, as viewed in the drawing, surfaces 'l2 and 'I3 engage and the member 63 is cammed over until its end snaps into position behind the step '14. This deflection of member 53 exerts pressure on the plunger I9, forcing it transversely of the backhead against the action of spring 2| far enough to unseat valve I8 and provide free ilow of pressure fluid to the motor. The provision of step 'I4 which takes the load of spring 2l eliminates any load upon the rotating clutch element 5|, which would otherwise be exerted through the walls of groove 6| and the shoe 62.

Operation-The idle condition of the tool is illustrated in Fig. 1, where the clutch elements are disengaged and the throttle valve is closed. When the operator applies the bit end of shaft 55 to the work and exerts pressure against the work the driven clutch element 5I is caused to move inwardly of the clutch housing I2 or toward the rear end of the tool, carrying with it the shoe 62 and the control member 63. The beveled surface 72 of the latter meets the in clined face 'I3 of block '1G below step 'I4 just before the clutch teeth 4l and 50 are brought into engagement, and upon continued pressure being applied the upper end of the control member is forced inwardly along the face 13, thereby pressing against the plunger I9 and opening the valve. The valve is unseated slightly before the clutch members engage. Hence the motor and the clutch member 43 are turning at a low rate of speed prior to clutch engagement, there- 4 by insuring smooth clutch action. When the teeth 4'1 and 5U have come into full engagement the end of control member 63 will move into engagement with the step 14 and will hold the throttle valve in full open position during the continued operation of the tool. It will be seen that with the end of the control member bearing on the step 'I4 there will be no axial pressure between the shoe 62 and either face of groove El, the clutch element 5| thus having no drag upon its movement as it is rotated to do the Work.

When the work has been completed, as for example when a screw S has been driven tightly into its socket, the resulting resistance to further rotation will be transmitted to the clutch teeth 5U and 47 and the inclined surface 48 of tooth 41 working against the inclined surface 49 of tooth 50 will cam the clutch element 5| downward or outward relatively. Simultaneously, shoe 62 will move relatively downward and will pull the upper end of control member 63 off the step 14, permitting spring 2| to seat throttle valve I8 and cut off the flow of pressure iiuid to the motor. rlhe tool will then cease to operate, and as soon as the operator withdraws it from the work spring 54 will further separate the clutch elements, causing the parts to again resume their positions of Fig. l.

Having thus described my invention, I claim:

1. In a power tool, a rotary fluid motor, a driving clutch element operatively connected with said motor, a driven clutch element, a throttle valve transversely arranged at the rear end of the tool and comprising a plunger, actuating means for said valve comprising a longitudinally movable member coupled with said driven element and extending across the extremity o1 said plunger, and means responsive to the longitudinal movement of said member for camming it inward to move said plunger and open said valve as the clutch elements come into engagement.

2. A power tool as claimed in claim 1, in combination with a longitudinally extending removable sheet metal cover forming an enclosure for said longitudinally movable member land carrying said camming means.

3. In a power tool, a rotary fluid motor, a driving clutch element operatively connected with said motor, a driven clutch element, a throttle valve transversely arranged at the rear end of the tool and comprising a plunger, spring means for pressing said plunger outward and closing said valve, actuating means for opening said valve comprising a longitudinally movable member coupled at one end with said driven element and eX- tending across the extremity of said plunger, -a cam for engaging the other end of said control member and camming the same inwardly to move said plunger and open said valve as the clutch elements come into engagement, said cam having a step therein acting as a backstop for said control member to take the load impressed by said spring pressed plunger in its valve open position.

4. In a power tool, a rotary fluid motor, planetary reduction gearing symmetrically disposed about the axis of said motor on the forward side thereof, a driving clutch element operatively connected with the output end of said reduction gearing, a driven clutch element, said elements being adapted to engage each other as one of them is shifted relatively toward the other, a throttle valve at the rear end of the tool, and actuating means therefor coupled with said driven clutch element extending alongside said motor and reduction gearing for opening the throttle valve as the clutch elements engage.

5. In a power tool, a rotary uid motor, a driving clutch element operatively connected with said motor, a driven clutch element, said elements being adapted to engage each other as one of them is shifted relatively toward the other, a throttle valve, said driven element having a peripheral groove therein, and actuating means for opening said valve when said driven clutch element comes into engagement with said driving element, said means comprising a longitudinally extending member having a shoe running in said groove.

6. In a fluid actuated rotary tool, a motor, a Work engaging member rotatable by said motor, a driving and a driven clutch element between said motor an-d member one movable relative to the other in one direction for transmitting rotation to said member and in the other direction for preventing transmission of rotation to said member, a throttle valve, spring means normally maintaining said throttle valve in a closed position, and means operatively associated with said throttle valve responsive to the movement of one of said elements in one direction for opening said throttle valve and in the other direction for en- -abling said throttle valve to be closed by said spring means.

7. In a uid actuated rotary tool, a motor, a work engaging member rotatable by said motor, a driving and a driven clutch element between said motor and member one movable relative to the other in one direction for transmitting rotation to said member and in the other direction for preventing transmission of rotation to said member, a throttle valve, spring means normally maintaining said throttle valve in a closed position, a throttle valve actuating member coupled with one of said clutch elements for movement therewith relative to the other, and cam means responsive to the movement of said throttle valve actuating member in one direction for causing it to press said throttle valve into open position.

EDGAR R. WHITLEDGE.

REFERENCES CITED The following references are of record in the iile of this :patent:

UNITED STATES PATENTS Number Name Date 1,229,570 Backscheider June 12, 1917 1,882,805 Gillett Oct. 18, 1932 2,261,204 Amtsberg Nov. 4, 1941 

